I. Field of the Invention
The present invention relates to an EMC shield for use, in particular, with a hot swap tray.
II. Background of the Invention
There is a requirement for modern electronic devices to emit as little electromagnetic radiation as possible as well as to be as resistant as possible to external electromagnetic interference or electrostatic discharges when in use. A universal solution is to surround devices with an electrically grounded shield. This is a relatively simple task when designing an individual device to be compatible with modern EMC requirements.
The task becomes more complicated when trying to shield groups of devices and, in particular, disk drives which form part of a disk array located in a rack. This is because each drive needs to have a shield which can link with the shields of adjacent drives to form a continuous shield. The traditional prior art solution, shown schematically in FIG. 1, has been to provide a tray 10, housing the disk drive 11, with a conductive vertically oriented shield 12 disposed between the disk drive housing and a front plate 15. Each tray 10 is inserted into the rack so that the disk drive 11 connects via a suitable plug and socket connector assembly 16 to a backplane 14. When inserted, the trays 10 are vertically spaced apart from one another so that their respective shields 12 are just touching, thus providing a continuous shield towards the front of the disk array. Usually the backplane 14 along with the body of rack acts to complete the electromagnetic enclosure.
The prior art solution requires the shield 12 to be resilient so that, on insertion of a drive, its shield may pass over another shield and flex back into contact with the other shield once the drive is fully accommodated to make an electrical connection and complete the shield. The prior art solution works well when trays are not inserted and removed frequently from the array.
New standards, however, allow trays to be hot swapped, so that they may be inserted and removed when the disk array is operational. Hot swapping is necessary in systems where down time must be avoided and where it is necessary to replace a faulty disk, to upgrade a disk with a faster or larger disk or simply to insert a disk carrying tray instead of a blank tray as storage requirements increase. Thus, trays are removed and inserted into disk arrays much more frequently than prior art solutions are designed to operate with.
It is an object of the present invention to mitigate such problems with shielding disks in a disk array.
Accordingly, the present invention provides a tray comprising a housing adapted to be slidably inserted in a rack, said tray including an electromagnetic shield member mounted for rotation about an axis traversing the sliding direction of said tray, said shield having a resting state in which said shield presents a first aspect in a plane traversing the sliding direction and a deflected state in which said shield presents a second aspect in said plane, said first aspect being greater than said second aspect, said shield being actuable on insertion of said tray into said rack to move from said resting state to said deflected state so that said shield clears adjacent shields located within the rack and from said deflected state to said resting state so that said shield engages said adjacent shields.
It will be seen that a tray including the shield mechanism according to the invention requires minimum insertion force and is not prone to wear in the manner of prior art solutions.